More elegant coding for merge_sort_fastest (#804)

* More elegant coding for merge_sort_fastest

* More elegant coding for merge_sort
This commit is contained in:
Tommy.Liu
2019-05-14 18:17:25 +08:00
committed by John Law
parent 70bb6b2f18
commit 3c40fda6a3
2 changed files with 55 additions and 44 deletions

View File

@ -29,36 +29,20 @@ def merge_sort(collection):
>>> merge_sort([-2, -5, -45])
[-45, -5, -2]
"""
length = len(collection)
if length > 1:
midpoint = length // 2
left_half = merge_sort(collection[:midpoint])
right_half = merge_sort(collection[midpoint:])
i = 0
j = 0
k = 0
left_length = len(left_half)
right_length = len(right_half)
while i < left_length and j < right_length:
if left_half[i] < right_half[j]:
collection[k] = left_half[i]
i += 1
else:
collection[k] = right_half[j]
j += 1
k += 1
while i < left_length:
collection[k] = left_half[i]
i += 1
k += 1
while j < right_length:
collection[k] = right_half[j]
j += 1
k += 1
return collection
def merge(left, right):
'''merge left and right
:param left: left collection
:param right: right collection
:return: merge result
'''
result = []
while left and right:
result.append(left.pop(0) if left[0] <= right[0] else right.pop(0))
return result + left + right
if len(collection) <= 1:
return collection
mid = len(collection) // 2
return merge(merge_sort(collection[:mid]), merge_sort(collection[mid:]))
if __name__ == '__main__':
@ -69,4 +53,4 @@ if __name__ == '__main__':
user_input = raw_input('Enter numbers separated by a comma:\n').strip()
unsorted = [int(item) for item in user_input.split(',')]
print(merge_sort(unsorted))
print(*merge_sort(unsorted), sep=',')